Kberhardt p



E. P. NICHOLSON.

s PARK PLUG. APPLICATION FILED MAY 15, l`9l9.

Patented Dec. 28, 1920.

l f ,f f f 1 f//f//l//f/ ////////////////////////l/ z f A TTORNEY UNITEDSTATS Thi'i" EBERHARDT P. NICHOLSON, OF BROOKLYN', NEW YORK, ASSIGN'OB,OF ONE-HALF TO CHARLES ROTH, QF NEW YORK, N. Y.

SPARK-PLUG.

Application led May 15, 1919.

To all whom t may concern Be it known that I, EBERHARDT l?. NICHOL- soN,a citizen of the United States, and a resident of the city of New York,borough of Brooklyn, county of Kings, and State of New York, haveinvented a new and Improved Spark-Plug, of which the following is afull, clear, and exact description.

This invention relates to spark plugs, and in particular to a new andimproved form of double electrode spark plug.

A purpose of the invention is to provide a double electrode spark plugadapted to give off' twin sparks, or a double spark within thecombustion chamber of the cylinder head of the internal combustionmotors.

A broad purpose of the invention is to provide a double electrode sparkplug which will simultaneously produce twin sparks to facilitatecombustion in the gas engine cylinder. It is also a purpose to providethe design of a double sparking ignition plug so as to make itunnecessary to employ two separate spark plugs in airplane engines, highspeed automobile racing motors, and large stationary working engines.

With the above and other objects in view the invention has relation to acertain combination of spark plug elements, an example of which isdescribed in the following specification, specifically pointed out inthe appended claims, and illustrated in the accompanying drawings,wherein:

Figure 1 shows the double electrode spark plug in side elevation, andFig. 2 shows a longitudinal sectional view taken through Fig. 1.

Fig. 3 shows a sectional view taken upon the line 3 3 of Fig. 2, andFig. 4 shows a sectional view taken upon the line 4 4 of Fi 2.

Figs. 5, 6 and 7 show modified forms of the spark plug, and arefragmentary views of the spark head. A description of the modified formwill be given inthe specification.

Referring now more in particular to the drawings, whereinthe same partsthroughout are designated by the same reference characters, the Anumeral1 points out a metal shell internally bored and adapted to receive theelements comprising the spark plug. .This shell is reduced in diametralsize and provided with screw threads 2 and shoulder 3. The spark plug isscrew-threaded into Specification of Letters Patent.

Patented Dec. 28, 1920.

Serial No. 297,331.

the motor cylinder and seated against gaskets or the cylinder face byengaging the shoulder 3 therewith. The shell is provided with internallugs 4 diametrically opposite one another and formed on the inner wallof the bore at right angles with the axis of said bore. The lugextremities will be terminated so as to leave an adequatecircumferential distance between the ends of each lug so as to admit aco-acting lug as later seen. The shell is provided with an internalflange 5 formed on the metal shell at the time it is centrally bored.The shell is provided with an inner shoulder 6 which is a formationincident to the shoulder 3 and which provides a bore sufficiently largeto receive a lug which co-acts with the lug 4 as later seen. rllhescrew-threaded shank 2 is fitted with spark terminal posts 8 and 9diametrically disposed thereon. These terminal posts are provided withspark heads 10. The shell is finished on the outside and upper portionthereof with a hexagonal wrench head for receiving the grip of a wrenchin order that the spark plug may be tightly screw-threaded into thetapped bore of the cylinder.

An insert core or plug 20 made of` any suitable heat resisting andelectric current resisting material is fitted within the shell. Theupper' portion of this core is provided with a screw-threaded stud 11.The core is provided with longitudinal parallel bores, and into thebores are tightly fitted circuit spark rods 12 and 13. These rodsproject through the lower portion of the heat resisting and insulatedinsert core or plug, and terminate adjacent the spark heads of theterminal posts. The spark heads and circuit spark rods will be spacedapart sufficiently to cause proper arcing between the respective circuitspark rods and spark terminal posts. The upper ends of the spark rodsare outwardly bent, and project through the cylindrical surface of theinsert core or plug as designated at 15 and 16. The screwthreadedextremities 15 and 16 are provided with suitable terminal washers andknurled retaining nuts 17. The upper end of the insert core is slottedas shown in Fig. 3 so that the spark rods may be introduced into thelongitudinal bores. After the rods are pushed into position the slotsare filled with insulating compound 18 which becomes an integral and.structurally composite part of the insert core. This firmly anchors thespark rods in position. A finishing head 19 is screw-threaded upon thescrew-threaded stud and thus locks the material 1S in place. and alsoprovides a smoothly finished and well appearing spark plug.

The insert core or plug will preferably have a diametral size slightlyless than the inner diametral size of the bore of the shell member 1.The insert core will very tightly fit the internal flange 57 and furtherwill very closely lit the internal bore of the screw-threaded portion 2.This lines up thc insert core within the shell causing the two membersto tightly engage one with the other. The insert core is provided withintegrally projecting lugs 22 diametrically formed upon thecircumference of the core and having a circumfr-nential lengthapproximately equal the distance between the lugs l ot' the shell. Theinsert core is pushed downwardly in the shell so that the lugs registerwith the opening between the lugs l. lVhen the insert core is in itsdownwardly limited position it is given a one-fourth turn which ausesthe lugs 22 to move into position behind the lugs el. This adequatelylocks the shell and insert core together. The core is grooved as shownat 23.

A heavy plastic form of heat resisting cement is used when assemblingthe shell and insert core. Cement is packed around the core so that itwill be tightly compressed within the annular space left between theinner wall of the shell and the outer wall of the core. This heatresisting cement material is designated by the numeral and tightly [itsinto the grooves 23 and also engags the co-acting lugs.' The cement isforced down in between the lugs 22 and shoulder 6. After the cementingmaterial is dried the insert core forms a very tight fitting immovableplug` within the shell. The cement becomes wedged into the grooves andbetween the surface of the lugs il and so as to form a solid andcomposite structure.

The shell member 1 and insert plug 20 may also be screw-threadedtogether in case it is undesirable to employ the lug retaining meansabove described.

In the manufacture of this spark plug it may be found preferable to usea plastic material for molding the insert plug within the shell member.This may be accomplished by packing the plastic material within theshell, and at the same time inserting the spark rods 12 and 18. Asuitable die will beemployed fork joining up with the shell member and'foi` finishing off the lower end ofthe insert plug. This may beaccomplished by screw-threading the shell member into a lower die,V saiddie to have a semicylindrical convexv form which will cause the plasticmaterial to mold itself within the die and impart; a rounded off headtol the projecting end of the molded insert plug. A finishing die willalso be employed on the upper portion of the shell member to finish ottthe top extended portion of the insert plug. This die will be properlyfitted to the shell member and after the plastic material has beencompressed into the spark plug shell and allowed to set and drysuiiiciently, the said dies will be removed therefrom and a well shapedinsert plug with top and bottom finished off according to the interiorshape of the dies. This form of construction will render unnecessary theuse of the finishing head 19 and will otherwise form a very substantialand composite structure. This method of manufacture will provide a sparkplug approximately solid and indestructible in nature.

The terminals 15 and 1G will be connected in the motor ignition systemon separate and independent high tension lines so that a separate andindependent spark can be transmitted through the two sets of spark heads10. In case one of the arcing sets 8-12 becomes inoperative and fails tospark, the other arcing set will function. This form of double electrodespark plug will adequately take the place of two spark plugs carriedwithin a single cylinder and render unnecessary the use of double plugs.

The last three figures of the drawings illustrate modified forms of thisspark plug and in particular relate to the lower form of the insertplug. In these views the insert plugs are designated by thc character B.The insert plug is either molded within the shell or separately huiltand pressed thereinto7 a disclosure of each method being hereinbeforedescribed.

The insert plug B is provided ou the lower end thereof with an extendedear C which projects beyond the end of the sparking sets. This extendedear is placed bctwe'en the sparking sets which. adequately separateseach set from the other and provides positive security against possibleshort circuits between the sparking sets.

The spark terminal posts 8 and f) are iutegrally made with, or fitted tothe outer rim of the screw-threaded .member 27 and the circuit sparkrods 12 and 13 are contained within the insert plug. Each set otsparking members S and 12. and 9 and 13. is separated by the extendedcar C. And each circuit spark rod is diametrieally located, likewise thespark terminal posts are diametrically located as shown in Fig. 7.

This forms a symmetrically constructed spark plug head. The extended earC projects below the sparking sets for the purpose of protecting themagainst possible damage or contact when the' plug is re'- meved from theengine t0A be cleaned. The extended ear C will also facilitate thebreaking up of .possible carbcn cel'lections, and

will further function to prevent any affinity of relation between thetwo separately disposed sparking sets.

Either form of the invention as presented may be manufactured under thepresent specications and claims without departing from the theory,scope, and breadth of the invention.

This double arcing plug, giving olf twin combustion are within anengine, will more readily ignite the compressed gas in an engine than asingle arcing plug will act.

This disclosure presents a spark plug which will fill a long-felt wantfor a motor ignition plug capable of running the engine under abnormallyhard conditions, and which will insure the automobilist or aviator of atleast one combustion arc at all times, by supplying his engine with adouble sparking means.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent is:

1. A spark plug, comprising in combination; an internally bored shellmember, an internal flange formed on one end thereof,

an internally bored shank formed on the other end thereof with theinternal periphery of the flange and bore of the shank approximatelyequal, an insert plug pressed into the shell member and tightly engagingthe flange and internal bore of the shank, a pair of spark terminalposts tted on the shell member, a pair of circuit spark rods fixed inthe insert plug, and a cementing material interposed between the shellmember and the insert plug to securely retain the shell and plugtogether.

2. A spark plug, including a shell formed with a bore, a core positionedwithin said bore, a rod extending within said core, said core beingformed with a screw threaded stud forming the upper part of said core,spark terminals secured to said sleeve and being adapted to coperatewith said rods, a head formed with a screw threaded opening adapted tobe attached to said stud, and a layer of insulating material interposedbetween said head and the upper end of said core.

EBERHARDT P. NICHOLSON.

